wool grease fatty acids recovered as a



United States Patent Oiifice i -32 ,25

LITHIUM BASE GREASE Richard A. Butcosk, Uniondale, N.Y., assignor to Socony Mobil Oil Company, Inc., a corporation of New York No Drawing. Original No. 2,842,493, dated July 8, 1958, Serial No. 623,290, November 20, 1956. Application for reissue February 25, 1959, Serial No. 795,572

12 Claims. (Cl. 25236) Matter enclosed in heavy brackets appears in the original patent but forms no part of this reissue specification; matter printed in italics indicates the additions made by reissue.

This invention has to do with greases characterized by a high order of elfectiveness over a wide range of operating conditions. More specifically, the invention is related to lithium base lubricating grease compositions which possess outstanding mechanical stability when worked in the presence of excess water, and which possess outstanding storage and service stability.

This application is a continuation-in-part of my copending application Serial No. 409,760, filed February 11, 1954, which has been abandoned.

In recent years, a demand has been created for greases of outstanding lubricating character which retain their grease structure during use over a wide range of operat ing conditions. For example, there has been an increas ing demand for water-resistant greases by the military and by such industries as steel mills, paper mills. and food canning. Until recently, lithium stearate greases have been sufliciently water-resistant to meet specifications an nounced by the military and industry. Now, however, specifications have been made more stringent in order that exellent lubricating performance be assured in service.

Lithium stearate greases have been designated as waterresistant or water-repellent, in accordance with their evaluation in the water washout test (Specification ANG- 5a) and the water-resistant test (Specification OS. 1350). A more severe water test, more recently announced, is that involving admixture of of water with the grease and working the resulting mixture in a motor-matic worker for 100,000 double strokes. This test is fully described in the Military Specification MIL-G-10924, Amendment 2. Conventional types of lithium soap greases particularly lithium stearate greases, work to a semi-fluid condition in this latter test. A number of steps have been taken to increase the water resistance of such greases. For example, free fat, such as high titer animal tallow, has been incorporated in the grease for this purpose. This approach appears to be disadvantageous or deleterious in other respects in that the fat is unstable and generally decomposes into fatty acids and glycerin, such that the grease eventually softens in storage and also in service. Other additives, such as zinc naphthenate and zinc resinate, have been used in greases to improve the Water-resistance characteristics, but they, too, soften with water.

It is an object of this: invention, therefore, to proivde a grease which retains its original character over a wide range of operating conditions. A primary object of the invention is to provide a grease composition characterized by excellent mechanical stability of lubricating quality and of grease-like structure, when worked in the presence of excess water. Another important object is the provision of a grease composition having excellent storage and service stability. Other objects of the invention will be apparent from the following description.

These and other objects have been realized by formation of new and novel lithium base compositions, which contain mixtures of lithium soaps in which the acid components of the soaps comprise balanced proportions of wool grease fatty acids and the aliphatic acids having at least about 12 carbon atoms per molecule, and which also contain relatively small amounts of calcium, strontium, barium'land/ or zinc soaps of said acids.

In my aforementioned application, Serial No. 409,760, I stated that I had found that calcium soaps, when present in the lithium greases described therein, destroyed the Water-resistance of such greases. Recently, I found that lesser quantities of calcium soaps imparted further improvement, rather than impaired, the lithium greases. Investigating further the effect of calcium soaps, I repeated my earlier work which is set forth in said application and was surprised to find that calcium soaps did not destroy the water-resistance feature. It is now clear that the lithium-calcium greases prepared earlier were faulty. It appearsthat the latter had not been properly prepared, particularly with respect to insulficient dehydration traceable to the use of lower temperatures than those which would lead to satisfactory dehydration.

Wool grease fatty acids are well known in the art. For example, they have been described in detail by E. S. Lower in the Industrial Chemist, in the March, May and October issues of 1947. As defined in the aforesaid publication, wool grease fatty acids are those fatty acids which are obtained when the soap solutions obtained in the manufacture of lanolin are acidified, may be extremely pale in color, or may be very dark to almost black, and may be nearly free from odour or have a strong acidic smell. They range from soft, limpid compositions to hard, wax-like materials, the latter usually being a paler product.

As further explained in the aforesaid publication, Wool grease fatty acids are composed, generally speaking, of the fatty acids obtained from the scouring liquids used in washing the wool in textile mills, and also the natural free wool wax acids and neutral saponifiable matter. They may also contain, depending upon the care taken in their manufacture and finish, traces of undecomposed soap from the manufacture of wool wax, and also traces of water soluble salts, mainly sodium sulfate, and also even traces of free sulfuric acid used in the decomposition of the above-mentioned soap.

Physical characteristics of wool grease fatty acids, and of a typical wool grease fatty acid product, are illustrated below in the following tabulation:

PHYSICAL CHARACTERISTICS OF WOOL GREASE FATTY ACIDS The above tabulation is descriptive particularly of wool grease fatty acids as produced in the United Kingdom. More recently in the U.S.A., with the advent of the recovery of lanolin alcohols and cholesterol from degras, Wool grease. fatty acids of somewhat different physical and chemical characteristics are available, and are a preferred material.

U.S.A. WOOL GREASE FATTY ACIDS RECOVERED AS A BY-PRODUCT OF LANOLIN ALCOHOLS AND CHOLES- TEROL MANUFACTURE As indicated above, the lithium soaps of this invention, used in conjunction with the lithium soaps of wool grease fatty acids, are soaps of aliphatic acids having at least about 12 carbon atoms per molecule. Representative of such acids are stearic acid, hydroxy stearic acids such as l2-hydroxy stearic acids, oleic acid, palmitic acid, hydroxy palmitic acids, myristic acid, hydroxy myristic acid, and the like. It is also to be understood that fatty materials containing substantial proportions of the foregoing acids can also be used herein. Typical of such materials are vegetable, animal and fish fatty oils, and hydrogenated fatty materials thereof, such as stearin, hydrogenated tallow fatty acids, hydrogenated soya bean fatty acids, hydrogenated fish oils and partial hydrogenated marine, vegetable, and animal oils. Preferred herein, together with the wool grease fatty acids, are stearic acid and palmitic acid, and myristic acid. A particularly outstanding grease is obtained with balanced proportions of wool grease fatty acids, stearic acid and hydroxy stearic acid.

One of the most critical relationships involved in the formation of the lithium base greases of this invention, is the balanced proportion of the lithium soap acid components. It has been found that the desired water-resistant characteristic is obtained only by using from about 15 percent by weight to about 80 percent by weight of Wool grease fatty acids, with the remainder of the acid components comprising aliphatic acids of the character described above. Outstanding grease compositions are obtained when the balanceof acid components comprises from about 25 percent by weight to about 50 percent by weight of wool grease fatty acids, with the remainder being the aforesaid aliphatic acids. For example, when lithium soaps of wool grease fatty acids are totally absent from corresponding lithium base grease compositions, the latter have unsatisfactory water-resistant characteristics. Even when the lithium soaps of wool grease fatty acids are present in combination with other lithium soaps, such as lithium stearate, but in inadequate proportion, the resulting compositions are found to be satisfactory. Such a grease composition is one wherein the lithium soaps of wool grease fatty acids represent less about 15 percent by weight of total fatty acid content. Another feature to be noted is a grease containing only lithium soaps of wool grease fatty acids, is inferior to greases of this invention; that is, such a grease sets up in prolonged storage or in other Words, the grease becomes much firmer in consistency such that it fails to lubricate properly when used.

The finished greases of this invention can be somewhat acidic, somewhat basic in reaction or can be neutral. That is, the finished greases can contain acid equivalent to as much as 0.5 percent by weight of oleic acid, or can contain alkali equivalent to as much as 0.2 percent by weight of lithium hydroxide.

As indicated above, the lithium grease compositions of this invention also contain small, but critical, quantities of calcium, strontium, barium and/ or zinc soaps. When calcium soaps are used, the mole ratio of lithium (Li) to calcium (Ca) should be between about 27:1 and about [6:1] 4 :1, with preference being given to mole ratios within the range of 14:1 to 9.5:1. soaps are used, the mole ratio of lithium (Li) to strontium (Sr) should be from about 42:1 to about 2.8:1; preference is given to mole ratios ranging from 14:1 to

When strontium 4.7:1. Correspondingly, with mixtures of lithium (Li) and zinc (Zn) soaps, the mole ratios are from about 30:1 to 5:1, preferably from 15:1 to 7.5:1. When barium soaps are used, the mole ratio of lithium (Li) to barium (Ba) should be from about 33:1 to about 3:1; preference is given to mole ratios ranging from 16:1 to 13:1. And in the same vein, when two, three or four of the soaps of the metals calcium, strontium, barium and zinc are used, the mole ratios of these metals related to the mole ratios of lithium will be between about 14:1 and about 4.7:1.

The total quantity of soaps is also balanced in order to provide greases of the desired character. The soaps comprise from about 5 to about 30 percent (by weight) of the finished greases, and preferably from about 7 to about 20 percent.

Inasmuch as methods for the preparation of lithium, calcium, trontium, barium and zinc soaps, and greases containing the same, are well known in the art, discussion of the same is believed to be unnecessary here. It is to be understood, however, that preformed soaps can be incorporated in oil to make the greases; and that the soaps can be formed in situ. Illustrative examples, however, are furnished hereinbelow as a guide.

It will be understood also that a variety of lithium, calcium, strontium, barium and zinc compounds can be used in preparing the soaps present in the new grease compositions. For example, lithium compounds such as the hydroxide, carbonate and hydride can be used. Generally, however, lithium hydroxide is preferred. Typical of the calcium compounds. useful herein are the hydroxide, oxide and carbonate, with the hydroxide being preferred. Typical of the strontium compounds suitable for use are the carbonate and the hydroxide octahydrate, the latter being preferred. Representative of the barium compounds are the hydroxide and hydroxide octahydrate, the latter-Ba(OH) .8H O-being preferred. Similarly, the following zinc compounds can be used: oxide, carbonate and stearate (pre-formed); the last mentioned is preferred.

The mineral oil constituent of the greases of this invention can be of varied character. The oil constituent is characterized by a viscosity (SUV) of greater than one second at 100 F., and generally from about 60 to about 6000 seconds at 100 F. The oil may be of naphthenic or of parafiinic character. Typical oils are a naphthenic mineral oil, having a SUV of 70 seconds at 100 F., and a solvent-refined, naphthenic oil having a SUV of seconds at F.

As indicated above, grease compositions of this i-nven tion can be prepared from pre-formed soaps, or the soaps can be made in situ in a grease-forming base of the character described above. It will be clear that when the soaps are prepared in situ by a procedure such as that illustrated below, there will be formed a mixture of wool grease fatty acid soaps and of the aforesaidaliphatic acid or acids, with the metals used being dis tributed between the said acids. When a mixture of lithium and calcium soaps are desired, then the resulting. mixture will comprise: lithium wool grease fatty acid soaps, a lithium soap or soaps of the aliphatic acid or acids, calcium wool grease fatty acid soaps and a calcium soap or soaps of the aliphatic acid or acids. Correspondingly, when the mixture to be formed is one of lithium and barium, or lithium and strontium, or lithium EXAMPLE I.LITHIUM-CALCIUM GREASE All of the fatty materials, wool grease fatty acidsandf for example, hydrogenated tallow fatty acids, and 30-40 percent of the total mineral oil, are charged to a suitable grease kettle. The resulting mixture is heated to about 140-160" F., and then the required proportion of lithium hydroxide monohydrate dissolved in water, is added. This is followed by addition of a water rinse. Next, the

the preparation. Thus, there is no addition of a dry hydroxide, as when Ca(OH) was used.

6 cone penetration is made. The value so obtained is taken as the initial penetration. A fresh sample. of the grease (unworked) is placed in another crucible (of the same size), and the crucible is stored in an oven at 160 dry Ca(OH) is added. After this, the mixture so ob- 5 F. for three days. At the end of the three-day period, tained is heated to 380-390 F., over a period of one the latter crucible is removed from the oven and is cooled to three hours. At this point, the balance of mineral to 77 F. A /2 scale cone penetration value is deteroil used in preparing the grease compositions, is added, mined for the sample so stored. The amount (percent) and the total mass is reheated to 390-400 F. for a of hardening of the grease under these accelerated conperiod of one to two hours. The resulting liquid product 10 ns is Calculated as: is withdrawn from the grease kettle intopans for cooling Percent hardening to room temperature (70-80 R), which cooling gen- 1 erally requires two to ten hours. The cooled blocks of e a A cone penetration grease, which are so obtained, are milled to a buttery lmtlal cone Penetratlon Product the desired Penetration. Correlation of the percent hardening" value with actual field storage conditions provides the following EXAMPLE II.-LITHIUM-STRONTIUM GREASE Scale; 7

h procedure f prepafing a lithi t fi grease and higher". Excessive hardening in 3-12 months is much the same as that given in Example 1. However, 20 f in this instance, the lithium and strontium hydroxides are 3140% dissolved in water and are added at the same stage of 540% Excellent to good- Results of the tests conducted with typical greases of this invention are given in Table I below.

Table I PHYSICAL CHARACTERISTICS OF GREASES MADE FRONT LITHIUM MIXED WITH OTHER METAL SOAPS Strontium Hydroxide (Sr(0H)2.8H5O), Peree Lime Flour (G3.(OH)2), Percent Zinc Stearate, Percent 1. Penetration Unworked/ Worked 256/277 259/283 253/292 268/288 280/300 50,000X is (Dry) Worker Test" 337 375 281 307 305 100,000X%" With 10% E20 342 361 335 340 362 acctle/lelgted I( Dven gst,d3 28m atIlSO" F.:

X one en. ore one en.

fioxfi Cone Pen X100 percent 32 22 29 1 9 29 ASIM Dropping Point, F 370 357 418 370 370 CRO Free Water Corrosion (14 Days-Distilled Water).. Pass Pass Pass Pass EXAMPLE III.LITHIUM-BARIUM GREASE Preparation of a lithium-barium grease is carried out in the same manner as given in Example II for a lithiumstrontium grease.

EXAMPLE IV.LITHIUM-ZINC GREASE The procedure for a lithium-zinc grease is the same as for a lithium-calcium grease, with the following change: the LiOH.H O is dissolved in water and the zinc stearate is added immediately thereafter.

Grease compositions of this invention have been subjected to several tests in order to determine their character in storage and in service under conditions simulating those encountered during their use.

The results shown in Table I indicate that firm lithium grease compositions, with satisfactory storage stability, can be prepared from wool grease fatty acids and stearic acid, and from a combination of lithium and a metal from Group II of Mendeleetis Periodic Table, the metal having an atomic weight from 40 to 137. All of the greases have excellent resistance to shear break down in the wet as well as dry conditions. It is to be noted, too, that all of the greases have high melting points, above 350 F. From a consideration of all results, the lithiumcalcium grease is considered to be outstanding.

Additional greases of the character contemplated herein are shown below in Table II. Here, the oil vehicle is of lower viscosity than that shown in Table I. Again,

One such test involves working the greases with ten the grease composltlons are of excellent characterpercent by weight of water, in a motor-matic worker Table II for 100,000 double strokes. This test is a measure of t mechanical stflbilittf of f P PQ t0 Mole Ratio Lithi'umto Calcium 41 141 water, and is described in Military Specification g fige sg g s g 3.85 3.85 Mme-10924. m ndm t 2. 53ft?2 .15.3233? 37?... 8.00 8.00

Another test measures the effectiveness of the grease i ig gg g g g 1. 5 1. 59 in preventing corrosion of metal parts to which the grease Mineral 5 8% 551 5 prgggggg'gag pgt 50 20 is applied. Thls IS the CRC free water corrosion test gg g 2- 23 86- which is described in Military Spec fication MIL- 50,O()0 s"Dr y Worker Test I 239 220 25013A. The test, 4.3.2.2 to 4.3.2.2.4 is known as bear- 7 W1th10%H20 288 271 g protection test Arfieleated Storage, 4 Days at F Percent ar emng. T 1 36 29 A third test used herein measures the stability of the ASTM PD E Pomt, F 324 7 grease under severe storage conditions. This is the accelerated oven test. In this test, a 60X worked sample is placed in a #0 Coors, low form, crucible. A /2 scale 7 8 soapsQ Conventional procedures can be used when mak- 3. A grease defined by claim 1, wherein the aliphatic ing use of the preformed soaps. The illustrative grease acid is stearic acid. compositions shown below were prepared in the following 4. A grease defined by claim 1 wherein the aliphatic mariner. -'I he wool grease fatty acid soap was miied acid is hydroxy-stearic acid. about thirty percent (bywei'ght') ofthetotal mineral oil; 5." A grease defined by claim 1 wherein the aliphatic themixture was heated to about 4-00" F'.,a'nd the resultacids comprise a mixture of stearic acid and hydroxyant;fn 1ixture,,was cooled; The conventional "aliphatic acid stearic-acid.

soap fii e the stearate) wa's mixed about thirty 6. A grease defined by claim 1 wherein the proportion t o the total mineral oil; this'niinture was heat ed of said mixture of soaps is from about 5 to about 30 gan din-like manner. The't'wo sdapmixtures' were '10 percent by weight of the grease.

combinedwith each other and with thercm ainder 7. A lubricating grease comprising a major proportion I 'o 1'ls; jf the resultin'g mixture was heated. to about of mineral oil and a minor proportion, suflicient to form F; The final product was cooled to 70-80" F. and,v a grease, of a mixture of lithium stearate and calcium .wlijen so cooled, was milled to a product of the desired' soaps of'wool grease fatty acids wherein the wool grease in 'T able III below:

penetration. Grease compositions so prepared are shown fatty acids component of the calcium soaps comprises 1 from about 25 percent byweight to about 50 percent by weight of the total acid components of the said lithium Table III V soap and said calcium soaps, and wherein the mole ratio PREFORMED SOAPS of lithium to calcium is withinthe range of from about 1 j, I 27:1 to about [6: 1] 4:1. 1 MOZEERMZ'O Lithit'tm i0 alumn 6:1 731 8. A lubricating grease comprising a major proportion fl m swarm, of mineral oil and a minor proportion, sufficient to form Lithiurn soaps oi'Wool a grease, of a mixture of lithium stearate and calcium Grease Fatty Acids, e tal soaps of wool grease fatty acids wherein the wool grease fatty acids component of the calcium soaps comprises from about percent by weight to about 50 percent by 50,000XM5" Dry Worker Test v weight of the total acid components of the said lithium iie s ltfitti litgtf' i Stil -trimmin s? 1 Said wherein mble e "Hardening 1 1s 33 of lithium to calclum is within the range of from about -T Pt YF% T -T---T .3 14:1 to about 9.51.

i 1 n I 9 A lubricating grease comprising a major proportion The results provided in Table III reveal that the two of mineral oil and a minor proportion, suflicient to form greases are of excellent character. Outstanding in regard] a grease, of a mixture of lithium and zinc soaps, the m st'o age st ability i h grease omprising lithium acid components of said soaps comprising about onejstearate and jcalcium; soaps of wool grease fatty acids 5 third y Weight of wool grease fatty acids and abouttWO- m; h d i value i o ly 18, 1 thirds by weight of stearic acid, and the mole ratio of It is' to be'understood that the greases of thisinven-f l m Z1110 being about 1511- tion can also contain'othercharacterizing materials. F 10.'A lubricating grease comprisinga major proportion "example; the greases can contain grease antioxidants such ofmillefal Oil and a minor Proportion, Suificient to form as amines, phenols, sulfides, etc.,*and lubricityimproving 40 a f a miXture of lithium and'stmnlium P e t h a free fat f ree fatty acids, esters of alkyl theacid components of said soaps comprising about oneand/Oi aryl acids,s ulfur ized fats-lead soaps, etc. These third by weight of wool grease fatty acids and about characterizing materials-do not'detract'from the'1ubricat-' thirds by weight of stearic acid, and the mole r i f ing valueof-the grease contemplated herein; rather, theselithium t0 Strontium being about 1411- characterizing materials serve to impart their customary A lubricatins grease pr ng a m j r p oporp'roperties to the grease. The amount of such additives tion of mineral and a minor P p sufficient to which can beadded to grease compositions of this inven f a e, of a mixture f lithium and barium soaps, tion is around about 0. 01 percent to less than 10 percent acid compflnellts O i 1 comprising about bywe'ight, and preferably 0.1 to 5'J0'percent by weight; One-third Y Weight of wool gfeas fatty acids and about Greases ofythis' invention are, applicable 1 for general two-thirds y Weight of stearic acid. and the l r io automotive uses; and" ar'e5excell'erit aircraft greases, inof lithium to barium being about 16:1.

dustrial greases and, the like. 12. A lubricating grease comprising a major proportion .I claim: v of mineral oil and a minor proportion, sufficient to form 1-. A-lubr-icatingcgreaselcomprising: a major propora grease, of a mixture of lithium, calcium and strontium tion' of mineral-oilz and a minor proportion, sufiicient to soaps, the acid components of said soaps comprising about form a grease, ofa r'nixture'of soaps, the acid components one-thirdby weight of wool grease fatty acids and about of said,soap 's'comprising from about fifteen percent by two-thirds by weight of stearic acid, the mole ratio of .weightto abouteighty percent by. weight of wool-grease lithium to calcium being about 14:1 and the mole ratio fatty acids and the balance of said acid-components comf li hi to strontium b i about 14;1

' said'soaps being lithium and at least one other metal comprising aliphatic acids having at least about twelve. carbon atoms per molecule, one of the metal components of References Citedin the file of this patent V or the ori al atent penent of said soaps. being selected from the group eongm p s'is tin'g of calciunt, strontium, b'ariumjand zinc, with the UNITED STATES PATENTS mole ratio of lithium (Li) to calcium (Ca) being between 1 about 27z-l and abo1'1t,[6: 1] 4:], the mole ratio of lithiurn 2,676,149 W O S et a1 Apr. 20, 1954 (Li) to strontium ('Sr being -between aboutz42:1 and about 2.8:1, the mole ratio er lithium (Li) to barium FOREIGN PATENTS (Ba) being between about 33:1 and about 3:1, and the 550,429

' mole ratio of lithium (Li) to zinc (Zn) being'between Great Britain Ian. 7-, 1943 about "3051 and about 5:1.

. OTHER REFEREN 2. A grease defined by claim 1 wherein the wool grease CES 1 fatty. acids comprise from about twenty-five percent by- Wool Wax, D. T. C. Gillespie, Hobart'luh-Co, Wash weight to about fifty-percent by weight of the total acid [components 1 I p p ington, DC, 1948, pp. 55 and 56. F 

